Several unrelated issues have assembled for what promises to be a wild month in the Minnesota Vikings' quarterback saga. An ominous diagnosis for Sam Bradford's knee and the potential return of Teddy Bridgewater have intersected, leaving open the possibility of a midseason transition that once seemed highly improbable.

The first is that "wear and tear" isn't a medical diagnosis. It's a description of why the injury happened. The real question to ask in order to understand Bradford's condition is: WHAT happened?

OK, genius: What happened?

The NFL Network reported that he suffered a bone bruise in the left knee in Week 1. That's the same knee in which Bradford has twice torn the ACL.

But I thought the Vikings said Bradford didn't have a bone bruise.

That's not actually what they said. Speaking to reporters Monday, athletic trainer Eric Sugarman said: "We're not dealing with a bone bruise from a direct hit."

See, there you go!

Well … as it turns out, there are two types of bone bruises. One can occur if, say, a helmet hits the shin. Another, as former San Diego Chargers team doctor David Chao has pointed out, happens with no contact. Technically, it's referred to as a periarticular bruise, and it occurs when the femur and tibia jam together without muscles absorbing the force.

Is that what Bradford has?

No one can say for sure except those who have seen Bradford's full medical report. But that's what Chao deduced in this analysis posted on the San Diego Union-Tribune website. I spoke with Chao by phone Wednesday, and he said that periarticular bruises are usually week-to-week injuries, not day-to-day.

So how long will Bradford sit out this time?

The Vikings are saying they will examine him daily, and I'm sure they will. But it's only fair to note that Bradford needed three weeks off just to attempt a return from the initial injury, and he still looked uncomfortable right away before suffering an aggravation. "These injuries are very difficult to manage and treat," Sugarman said.

Well, at least this is an injury that will heal fully in time for 2018.

Perhaps, but that brings us to our second takeaway. Bradford turns 30 next month and his contract expires after the season. As recently as this summer, given Bridgewater's status, the assumption was that the Vikings hoped to re-sign Bradford. Don't forget: They gave the Philadelphia Eagles a first-round draft choice, which turned out to be the No. 14 overall pick in 2017, to acquire him after Bridgewater's injury in August 2016. The Vikings considered Bradford more than a short-term replacement.

So why would a bone bruise change that plan?

Because it only adds to a long list of knee ailments Bradford has suffered since entering the NFL in 2010. How much money, and commitment, would you invest in a quarterback who not only has multiple ACL injuries on his résumé but also "wear and tear" that might have contributed to a corresponding injury and an extended absence?

Wow. Good thing Bridgewater is almost ready.

Honestly, we all need to slow our roll on that one.

Come on, I'm too hyped.

Let's just be realistic for a moment. Bridgewater hasn't practiced since enduring a catastrophic injury to his left knee nearly 15 months ago. The injury was so severe that the team rushed him to a Level 1 trauma hospital for fear that he could lose part of his leg. While the Vikings have always said they hoped he would return, details on his progress have been scarce, and we have never received a full accounting of the injuries he suffered that day.

But we've seen video of him dropping back and throwing!

Yes, we have. But as anyone would tell you, there is a big difference between rehabilitation work (off to the side) and practicing, let alone playing in a live game.

So what do we know about Bridgewater?

Further complicating matters, Case Keenum is making an argument to remain in the Vikings' quarterback plans. AP Photo/Darron Cummings

He is on the reserve/physically unable to perform list (PUP) and is scheduled to undergo an exam Monday to update his recovery. If he is medically cleared, the Vikings could open a three-week window that amounts to a roster exemption. It would allow Bridgewater to practice fully with the team but not count against their 53-man roster. At the end of that window, or at any point before that, they could activate him to the roster and make him eligible to play.

So, if my math is right, Bridgewater technically could be eligible to play in Week 7 against the Baltimore Ravens?

Yes, but that almost definitely won't happen. I can't imagine the Vikings -- or any other team -- using a starting quarterback with one week of practice over a 15-month period.

Are the Vikings required to open the window next week?

No. They can start the process at any point after the sixth week. [Note: An earlier version of this post indicated a Week 11 deadline. That rule was eliminated in March during the NFL owners meeting.]

What if they decide he isn't ready to play at the end of the three-week window?

Then he moves to injured reserve and misses the rest of the season.

Let's be more positive than that. Is he the Vikings' starter if and when he is activated to the roster?

I'm not so sure about that. Even if you remove Bradford from the equation, backup Case Keenum has played pretty well. His Total Quarterback Rating of 68.0 ranks fifth among qualified quarterbacks. The Vikings are 3-2 at the moment and in position to contend for a playoff spot. If Keenum maintains his current pace, an argument could be made for leaving him on the field regardless of Bridgewater's status. The approach might be different if the Vikings are out of contention near the end of the season.

If they don't play Bridgewater, how will they decide whether to re-sign him this offseason?

His contract, like Bradford's, is scheduled to expire after the season. But NFL rules are dicey when it comes to PUP players in the final year of their deals. The collective bargaining agreement allows teams to roll over the contracts of players on the PUP if they are still "physically unable to perform" by the sixth week of the season, according to the exact language.

What does that mean?

It's a little vague. Does that mean the window needs to be opened after Week 6? Does the player need to be added to the 53-man roster? If challenged, the NFL would need to clarify for both the Vikings and Bridgewater.

Ultimately, if Bridgewater gets back on the field and demonstrates he is healthy, I don't think the Vikings would reward his hard work by dealing him a contractual blow. So the guess here is that Bridgewater's contract won't be "tolled," as it's called, unless he misses the entire season.

Wow, there are a lot of moving parts here.

Indeed. To sum it up: Bradford has a knee injury that is more serious than day-to-day and adds a new level of concern about his future. Bridgewater is approaching the first of many hurdles he'll need to clear before anyone can say that he is ready to resume his career. And in the meantime, the Vikings' only healthy and experienced quarterback is having a career year. Stay tuned.